Free radicals associated with DNA damage.

This short review focuses on the chemical events related to DNA damage induced by free radicals. Diffusible hydroxyl radicals (HO) are able to react with either the sugar units by hydrogen abstraction or with the base moieties by addition. Selectively generated carbon-centred radicals at C1', C4' and C5' in model nucleosides or oligonucleotides and their subsequent fate under aerobic or anoxic condition are discussed by rationalisation of the available kinetic data. Reaction paths for the formation of nucleobase modifications such as 8-oxoG and FapyG, amplification of base damage, and tandem lesions are also discussed. Some types of DNA damage may be poorly repaired leading to deleterious genetic changes with time.